Journalist’s eulogy of Hawaii’s GMO papaya backfires, writes Claire Robinson in the third and final part of a series

In Part 1 of this series we saw how Saletan used his Slate magazine piece to blame the critics of golden rice for the blindness and death of countless malnourished children, without making it clear that the real reasons this GMO crop is still unavailable are: 1. it has failed its field trials;2. it hasn’t been safety tested;3. it hasn’t even been shown to help the malnourished.

Saletan also omitted to mention that tried and tested approaches to tackling vitamin A deficiency have already achieved a rapid reduction in the problem in the Philippines, the main target country for golden rice.

In Part 2 we also considered Saletan’s sins of omission. We saw how he sought to bury the fact that the World Health Organization’s experts had declared the herbicide with which over 80% of the world’s GMO crops are grown a “probable human carcinogen”, while his authority for claiming that “experts agree” glyphosate is “relatively benign” was a report by US Dept of Agriculture economists that contained no evidence that could possibly support such an assertion.

But perhaps Saletan’s greatest omission is his total silence about the escalating problems in countries like Argentina and Brazil, where the widescale use of GMO crops has been associated with an explosion in pesticide use and in pesticide-related illnesses.

There is not one mention in Saletan’s long article of the countries that have the second and third largest GMO crop cultivation areas in the world, let alone of the problems they are facing. But Saletan goes to great lengths to hype the value of GMO crops that are either unavailable, like golden rice, or little grown, like GMO papaya.

GMO papaya to the rescue?

Saletan showcases the GMO papaya early on in his prolonged attack on GMO critics. He repeats the industry line that the GMO ringspot virus-resistant papaya is a “triumph” that “saved” the Hawaiian papaya industry. But although the GMO papaya has largely dominated that industry since the late 1990s, papaya production today is only about half what it was in the 1980s.

Critics, in fact, contend that the virus problem could have been managed without any use of GMO papaya and they see its widespread market rejection as an important factor in the marked decline of Hawaiian papaya production. According to Melanie Bondera, a board member for the NGO Hawaii Seed, GMO promoters are “not looking at the bigger picture of the economic problems that come with it – the cross-contamination, the market loss, the testing costs... The bottom line is the GMO papaya has never sold for as much as the non-GMO papaya.”

Saletan does not understand genetic engineering

Saletan berates those who raise safety concerns about the GMO papaya, portraying them as zealots who “reject the evidence and cling to their faith in a GMO apocalypse”. But Saletan’s own apparently unshakeable faith in the safety of GMO papayas merely demonstrates how little he understands genetic engineering

He quotes the US Environmental Protection Agency as saying that for many years people have been eating the ringspot virus in whole form, so there can be no additional risk in eating a GM papaya engineered to contain the viral coat protein that confers resistance to the ringspot virus.

But in making this argument, he fails to grasp a fundamental aspect of GMO safety. In crop genetic engineering, the source of the gene of interest is not the sole factor that decides whether the final GMO is toxic or allergenic. Context is crucial. How the gene behaves in its new host matters. The information conferred by the introduced DNA, not the origin or substance of the DNA, is what must be assessed.

Saletan also seems unaware that the genetically engineered form of the virus is not the same as the natural virus. In order to get the viral gene into the papaya, the gene sequence has to be joined up with DNA from a variety of sources, including an antibiotic resistance coding sequence from E. coli bacteria, promoter and terminator sequences from a soil bacterium, and a promoter sequence from another plant virus. No one knows the long-term effects of eating plants engineered with these combinations of DNA sequences.

In addition, the GM gene insertion and subsequent tissue culture processes used in genetic engineering create mutations. These can result in biochemical changes in the plant, which in turn could make the plant unexpectedly toxic or allergenic.

No doubt Saletan would dismiss such points of concern as fearmongering. But the reason these cautions are still lively in the minds of scientists and regulators, and not just campaigners, is that toxic and potentially toxic effects have been detected in animals fed GM plants. These effects were unexpected, as the GM plants are claimed by GMO proponents to be the same as their non-GM parent plants except for the deliberately inserted trait – for example, herbicide tolerance.

Such is the resistance to replicating and extending research that finds problems with GM crops that scientists still do not know which aspect of the genetic engineering process or subsequent cultivation methods caused the ill effects. Possible culprits include the intended gene product (for example, the Bt toxin in GM Bt insecticidal crops), the pesticide that the GM crop is engineered to be grown with, or biochemical changes in the plant arising from mutations in the host DNA caused by the GM gene insertion. It is unforgiveable that these uncertainties remain 20 years after GMOs were introduced into the food supply.

Perhaps the greatest irony in this tale of technological fumbling is that since 2011 there has been no need to take risks with GM papaya because a non-GM ringspot virus-resistant variety has been available. As is so often the case with such non-GM breakthroughs, the non-GM papaya has received little publicity or hype.

Saletan also berates a Hawaii Council member who sponsored a bill proposing a ban on GMO cultivation for refusing to say, “regardless of the evidence”, that GM papaya was safe to eat.

Saletan’s evidence for the safety of GM papaya is a Chinese study in which rats were fed GM papaya and another group of rats were fed non-GM papaya. Saletan says the study found “no resulting differences between the rats”.

But it appears that he has not read the study. In spite of the fact that the experiment only followed the rats for 28 days, statistically significant differences were found in the GM papaya-fed animals. These included:

* Changes in clinical biochemistry – measurements of key substances in blood and urine that help with the diagnosis of diseases. In a 28-day rat feeding study (equivalent to only 7–8 years in a human), there is no way of knowing whether these changes are a temporary blip or early signs of kidney or liver toxicity.

Too-short studies can only show acute toxicity

The only thing that feeding GMOs to rats in a 4-week study can tell us is whether the GMO is acutely toxic. Usually what happens is that no rats drop dead from eating the GMO within the four short weeks of the study. This shows it is not acutely toxic. It’s not, in Saletan’s words, “a GMO apocalypse”. But you don’t drop dead on the first exposure to cigarette smoking or low-level lead contamination in foods, either – though few would claim that they are safe.

What is repeatedly found in these short studies on GMOs are statistically significant differences in kidney and liver function and an immune response in the GM-fed animals. All too often, industry-friendly authors dismiss such findings as not biologically significant. This is exactly the line taken by the Chinese researchers in the GM papaya experiment. But they have zero evidence for this claim, since they did not extend the study length to a long-term period to see what happened to the disturbances over time: did they disappear, or did they escalate into serious disease?

Two decades’ worth of 4-week animal feeding studies with GMOs has taught us that such short studies are useless. They do not show the GM food is safe over the long term.

GMO skeptic attacked by Saletan was right

The findings of the rat feeding study with GM papayas can tell us only one thing with any certainty. The Hawaii Council member who refused to say GM papaya was safe was right. And Saletan, despite his patronising attitude towards her and other GMO critics, is wrong.

Saletan’s conclusion on GM papaya safety is telling. He writes, “Some people, to this day, believe GE papayas are dangerous. They want more studies. They’ll always want more studies. They call themselves skeptics. But when you cling to an unsubstantiated belief, even after two decades of research and experience, that’s not skepticism. It’s dogma.”

What about when you cling to an unsubstantiated belief that the GM papaya is safe, against the evidence from the sole inadequate animal feeding study, and in spite of massive data gaps caused by the failure of the industry to test it for safety over long-term periods? By Saletan’s own definition, this is not the skepticism we expect of journalists. It’s dogma.

It is part of Saletan’s dogma that the GMO papaya is not just unquestionably safe but a “triumph” and a saviour. He also portrays golden rice as a saviour that can prevent death and blindness, despite the fact that it’s both unproven and unavailable. Those who question his triumphal vision are portrayed as heretics desperately clinging to their “faith in a GMO apocalypse” – as opposed to Saletan’s faith in a GMO rapture that could be ushered in if only we could silence the dreadful “army of quacks and pseudo-environmentalists waging a leftist war on science.”